1. Field of the Invention
The present invention relates to generating image data as the blending of a plurality of samples.
2. Description of the Related Art
Advances in the field of digital signal processing have allowed many new developments to be effected in video and film post production. Many sophisticated image modifications and special effects have become widely accepted as part of post-production procedures.
Often, post-production techniques are used to generate additional image data to be composited within frames of original video or film footage, either because said additional image data cannot be realistically committed to movie or video film, for instance if the movie script requires an actor to jump over a mile-wide gap, or because it does not exist, for instance if the movie script requires photo-realistic alien spaceships.
The degree of realism conveyed by such image data is traditionally paramount in order to immerse an audience within the narrative, and techniques are known with which to motion-blur the additional image data when such data portrays moving objects or actors. Motion is usually a function of the position of an object changing in each frame of a sequence of frame. Displaying such a sequence at the appropriate speed, for instance 24 frames per second for movie films, provides the audience with the illusion of movement. Motion-blurring techniques are used to enhance this illusion, and are especially relevant when the object in question is moving at a fast pace. Motion blurring traditionally involves specifying a shutter length indicative of the number of frames to use to evaluate the motion of an object thereon, and a number of samples which defines how many snapshots are taken of each of said frames, whereby said samples are subsequently blended and the output of said blending operation is an output frame showing said object with motion-blur.
A problem however exists in motion-blurring techniques according to the known prior art, in that additional objects as described above have to be independently motion-blurred if artistic considerations or the movie script requires discrete degrees of motion-blurring for each additional object in the same frame, for instance if two alien spaceships are flying at different speeds, because said motion-blurring techniques according to the known prior art require the shutter length and the number of samples be configured for the entire scene or output frame. This may generate visible artefacts which are highly undesirable to convey the required degree of realism.
Moreover, the independent motion-blurring of said additional objects is very resource-intensive, because a separate output frame may be required for each of said motion-blurred objects, to be composited at a later stage with the original movie or video footage.
An embodiment of the invention will now be described by way of example only with reference to the abovementioned drawings.